Close physical human-robot interaction (pHRI) is one of the great challenges in robotic research. Some robot systems have already attained the requisite control-technology capabilities to perform delicate and complex manipulations as well as human-robot interaction (HRI) tasks that require a dynamic exchange of forces between the robot and the environment. In this context, reference is made to the following publications: A. Albu-Schïffer, S. Haddadin, C. Ott, A. Stemmer, T. Wimböck and G. Hirzinger, “The DLR Lightweight Robot Lightweight Design and Soft Robotics Control Concepts for Robots in Human Environments”, Industrial Robot Journal, vol. 34, pp. 376-385, 2007, and D. Shin, I. Sardellitti, and O. Khatib, “Hybrid actuation approach for human-friendly robot design”, in IEEE Int. Conf. on Robotics and Automation (ICRA 2008), Pasadena, USA, 2008, pp. 1741-1746.
This approach has made it possible, for instance, to carry out difficult assembly tasks that, up until now, had been performed manually. In particular, the achieved delicate and fast manipulation capabilities of these robots help in avoiding damage to potentially fragile objects, in addition to which they are fundamentally far less dangerous to the humans who are going to interact with the device. In this context, reference is made to the followings publications: N. Hogan, “Impedance control: An approach to manipulation: Part I—theory, Part II—implementation, Part III—applications”, Journal of Dynamic Systems, Measurement and Control, vol. 107, pp. 1-24, 1985, S. Haddadin, A. Albu-Schïffer, A. D. Luca and G. Hirzinger, “Collision detection & reaction: A contribution to safe physical human-robot interaction”, in IEEE/RST Int. Conf. on Intelligent Robots and Systems (IROS2008), Nice, France, 2008, pp. 3356-3363, and A. De Luca and R. Mattone, “An Adapt-and-Detect Actuator FDI Scheme for Robot Manipulators”, IEEE Int. Conf. on Robotics and Automation (ICRA 2004), New Orleans, USA, pp. 4975-4980, 2004.
In order to allow such physical interaction between humans and robots, there has been a great deal of interest in removing classic safety barriers such as protective fences or light sensors for “human-friendly” robots that are capable of direct interaction. For purposes of defining the required safety regulations, it is, of course, necessary to first understand what a robot for such tasks should be like and also how it is controlled, so that it can operate safely in a human environment. Here, it must fundamentally be ensured that a human will not suffer any severe injuries, even in a worse-case scenario. Based on the pioneering work of Yamada, in which human tolerance to pain was introduced as a safe collision criterion of a robot, others have expanded this field of research. In this context, reference is made to the publication by Y. Yamada, Y. Hirasawa, S. Huang, Y. Umetani and K. Suita, “Human-robot contact in the safeguarding space” IEEE/ASME Transactions on Mechatronics, vol. 2, no. 4, pp. 230-236, 1997.
In particular, new drive technologies, interaction-regulation algorithms and robot-human collision-injury models have been introduced. In this context, reference is made to the following publications: K. Ikuta, H. Ishii, and M. Nokata, “Safety evaluation method of design and control for human-care robots”, The Int. J. of Robotics Research, vol. 22, no. 5, pp. 281-298, 2003, A. Bicchi and G. Tonietti, “Fast and soft arm tactics: Dealing with the safety-performance tradeoff in robot arms design and control”, IEEE Robotics and Automation Magazine, vol. 11, no. 2, pp. 22-23, 2004, M. Zinn, O. Khatib, B. Roth, and J. K. Salisbury, “A new actuation approach for human-friendly robot design”, International journal of Robotics Research, vol. 23, no. 4/5, pp. 379-398, 2005, J. Heinzmann and A. Zelinsky, “Quantitative safety guarantees for physical human-robot interaction”, The Int. J. of Robotics Research, vol. 22, no. 7-8, pp. 479-504, 2003, S. Oberer and R.-D. Schratt, “Robot-dummy crash tests for robot safety assessment”, in IEEE Int. Conf. on Robotics and Automation (ICRA 2007), Rome, Italy, 2007, pp. 2934-2939, J.-J. Park and J.-B. Song, “Collision analysis and evaluation of collision safety for service robots working in human environments”, in Advanced Robotics, 2009. ICAR 2009. International Conference on, 2009, pp. 1-6, D. Gao and C. Wampler, “On the use of the head injury criterion (HIC) to assess the danger of robot impacts”, IEEE Robotics and Automation Mag., vol. 16, no. 4, pp. 71-74, 2009, B. Povse, D. Koritnik, R. Kamnik, T. Bajd, and M. Munih, “Industrial robot and human operator collision”, in IEEE Int. Conf. on Systems Man and Cybernetics (SMC 2010), Istanbul, Turkey, 2010, pp. 2663-2668, S. Haddadin, A. Albu-Schïffer, and G. Hirzinger, “Safe Physical Human-Robot Interaction: Measurements, Analysis & New Insights”, in International Symposium on Robotics Research (ISRR 2007), Hiroshima, Japan, 2007, pp. 439-450, M. Wassink and S. Stramigioli, “Towards a novel safety norm for domestic robots”, IEEE/RS J. Int. Conf. on Intelligent Robots and Systems (IROS 2007), San Diego, USA, pp. 3243-3250, 2007, and ISO 10218, “Robots for industrial environments—Safety requirements—Part 1: Robot”, 2006.
This fact shows that the analysis and the understanding of injuries in the realm of robotics are an essential prerequisite in order to make genuine pHRI possible, also in actual applications.
In recent years, some of the first safety studies in robotics have been carried out, which provide insights into the potential injuries that humans would suffer as a result of a collision with a robot. In this context, reference is made to the following publications: S. Haddadin, A. Albu-Schïffer, and G. Hirzinger, “Safety Evaluation of Physical Human-Robot Interaction via Crash-Testing”, Robotics: Science and Systems Conference (RSS2007), Atlanta, USA, 2007, “Requirements for Safe Robots: Measurements, Analysis & New Insights”, Int. J. of Robotics Research, vol. 28, no. 11, pp. 1507-1527, 2009, S. Haddadin, A. Albu-Schïffer, M. Frommberger, J. Roβmann, and G. Hirzinger, “The DLR Crash Report”: Towards a Standard Crash-Testing Protocol for Robot Safety-Part I: Results”, in IEEE Int. Conf. on Robotics and Automation (ICRA 2008), Kobe, Japan, 2009, pp. 272-279, and J. Park, S. Haddadin, J. Song, and A. Albu-Schïffer, “Designing optimally safe robot surface properties for minimizing the stress characteristic curves of human-robot collisions”, in IEEE Int. Conf. on Robotics and Automation (ICRA 2011), Shanghai, China, 2011, pp. 5413-5420. So far, the discussion and analysis of various worst-case HRI scenarios have been conducted according to the following scheme:    1) selection and/or definition and classification of the type of collision    2) selection of the applicable injury analysis method    3) assessment of the potential injury to a human    4) quantification of the influence of the relevant robot parameters    5) assessment of the efficiency of the countermeasures for minimizing and/or preventing injuries
This analysis yielded the foundations of injury processes, for instance, in the case of fast, blunt impact, dynamic and quasi-static pinching, or cuts and punctures caused by sharp tools.
It can be generally summarized that the analysis of injuries became a significant part of robot research since the international standard associations have also started to adopt requirements for safe robots. The fact that there is an expectation that it should be possible to limit potential injuries to very minor blunt injuries also underscores the general need to become involved in this interdisciplinary field. The sooner research yields new insights into understanding injuries in the realm of robotics, the sooner it will be possible to introduce HRI tasks in the real world.
Another unsolved problem in the realm of safety in robotics is how to incorporate the rather general understanding of injuries into regulations that apply to robots. Insights into injuries in the realm of robotics are normally employed to promote a safer mechanical design or to demonstrate that a given mechanical design has a positive influence on potential injuries in the case of an accidental collision. Up until now, knowledge about injuries has not been explicitly incorporated into the regulations as a restriction that has to be observed.
Moreover, German patent application DE 10 2009 051 146 A1 discloses a device used in iron and steel works and/or in rolling mills comprising a robot that is controlled with types and modes of operation that influence an associated human-robot interface and that are configured so as to be adapted and/or adaptable to varying degrees of automation of the robot and/or to a different time-related and/or location-related positioning of humans and robots as interacting members in a workplace, whereby the robot, especially an industrial robot, is associated with at least one protected area that is monitored by detection elements that interact with the robot, especially an industrial robot, whereby the extension and functionality of said protected area are configured so as to be varied and/or variable in terms of the robot activities and/or the robot working positions, and whereby the robot, especially an industrial robot, is arranged on or in a moving device that can run on a track surface so as to create a solution that allows a more flexible adaptation of a robot or robot system to different degrees of human-robot interaction as well as a more flexible use of an industrial robot within the scope of work activities and work flows in a large-scale plant, especially iron and steel works.
Moreover, German patent application DE 102010 063 208 A1 discloses a method for operating a safety mechanism for a handling device, especially an industrial robot, having a movable gripper and having at least one sensor that at least largely surrounds the gripper in order to detect at least potential collisions with objects that are in the path of movement of the gripper, whereby, if the risk of a collision is detected, a signal is generated by a control unit, resulting in a change in the movement sequence of the gripper along its path of movement, wherein the changed movement sequence is a controlled reduction in the speed of movement of the gripper, so that a method for operating a safety means for a handling device, especially an industrial robot, is refined in such a way that it is possible to easily restart or continue to operate the handling device once the risk of a collision has been eliminated.